In view of the wide variety of products that are sold for being dispensed from containers, particularly containers with round necks which define the dispensing portal, numerous constructions have evolved for container stoppers or closure means for the portals, including for example screw caps, stoppers, corks and crown caps, to name a few. Generally, products such as vinegar, vegetable oils, laboratory liquids, detergents, honey, condiments, spices, alcoholic beverages, and the like, have similar needs regarding the type and construction of the closure means used for containers for these products. However, wine sold in bottles represents the most demanding product in terms of bottle closure technology. In an attempt to best meet these demands, most wine bottle closures or stoppers have been produced from a natural material known as “cork.”
While natural cork still remains a dominant material for wine closures, wine closures from alternative materials such as polymers have become increasingly popular over the last years, largely due to the shortage in high quality natural cork material and the awareness of wine spoilage as a result of “cork taint,” a phenomenon that is associated with natural cork materials. In addition, these closures from alternative materials such as polymers have the advantage that by means of closure technology, their material content and physical characteristics can be designed, controlled and fine-tuned to satisfy the varying demands that the wide range of different wine types produced throughout the world impose on closures.
One of the principal difficulties to which any bottle closure is subjected in the wine industry is the manner in which the closure is inserted into the bottle. Typically, the closure is placed in a jaw clamping member positioned above the bottle portal. The clamping member incorporates a plurality of separate and independent jaw members which peripherally surround the closure member and are movable relative to each other to compress the closure member to a diameter substantially less than its original diameter. Once the closure member has been fully compressed, a plunger moves the closure means from the jaws directly into the neck of the bottle, where the closure member is capable of expanding into engagement with the interior diameter of the bottle neck and portal, thereby sealing the bottle and the contents thereof.
In view of the fact that the jaw members are generally independent of each other and separately movable in order to enable the closure member to be compressed to the substantially reduced diameter, each jaw member comprises a sharp edge which is brought into direct engagement with the closure member when the closure member is fully compressed. Score lines are frequently formed on the outer surface of the closure member, which prevents a complete, leak-free seal from being created when the closure member expands into engagement with the bottle neck. This can occur, for example, if the jaw members of the bottling equipment are imperfectly adjusted or worn. Leakage of the product, particularly of liquid product, from the container can thus occur.
Thus, it is generally desirable that any bottle closure be able to withstand this conventional bottling and sealing method. Furthermore, many cork sealing members also incur damage during the bottling process, resulting in leakage or tainted wine.
Another issue in the wine industry is the capability of the wine stopper to withstand a pressure build up that can occur during the storage of the wine product after it has been bottled and sealed. Due to natural expansion of the wine during hotter months, pressure builds up, which can result in the bottle stopper being displaced from the bottle. As a result, it is generally desirable that the bottle stopper employed for wine products be capable of secure, intimate, frictional engagement with the bottle neck in order to resist any such pressure build up.
A further issue in the wine industry is the general desirability that secure, sealed engagement of the stopper with the neck of the bottle be achieved quickly, if not virtually immediately after the stopper is inserted into the neck of the bottle. During normal wine processing, the stopper is compressed, as detailed above, and inserted into the neck of the bottle to enable the stopper to expand in place and seal the bottle. However, such expansion desirably occurs immediately upon insertion into the bottle since many processors tip the bottle onto its side or neck down after the stopper is inserted into the bottle neck, allowing the bottle to remain stored in this position for extended periods of time. If the stopper is unable to rapidly expand into secure, intimate, frictional contact and engagement with the walls of the neck of the bottle, wine leakage can occur.
It is further desirable that the closure be removable from the bottle using a reasonable extraction force. Although actual extraction forces extend over a wide range, the generally accepted, conventional extraction force is typically below 100 pounds (445 Newtons).
In achieving a commercially viable stopper or closure, a careful balance must be made between secure sealing and providing a reasonable extraction force for removal of the closure from the bottle. Since these two characteristics are believed to be in direct opposition to each other, a careful balance must be achieved so that the stopper or closure is capable of securely sealing the product, in particular the wine in the bottle, preventing or at least reducing both leakage and gas transmission, while also being removable from the bottle without requiring an excessive extraction force.
Furthermore, it is generally desirable to effectively prevent or reduce oxygen from entering the bottle. Too much oxygen can cause the premature spoilage of wine. In fact, oxidation may occur over a period of time to render the beverage undrinkable. Thus, it is desirable that the closure has a low oxygen permeability in order to extend and preserve the freshness and shelf life of the product. Apart from reducing the oxygen permeability of the closure, additives that act as oxygen scavengers can be incorporated into the closure. Oxygen migrating through the closure is then quenched by the additive. A combination of a low oxygen permeability and oxygen scavengers inside the closure is particularly effective at reducing oxygen-mediated spoilage of wine. Any commercially viable wine stopper or closure should therefore generally have a low oxygen transfer rate (OTR).
In addition to the above, it is also desirable, for economic and environmental reasons, to reduce the total amount of material in a closure from alternative materials such as polymers, particularly the amount of polymer material. Since the size of the closure is determined by the size of the bottle neck, reducing the amount of material can principally be achieved by reducing the density of the closure, in particular of the core member, which is generally in the form of a foamed material comprising air- or gas-filled cells. However, reducing the density of the core member generally increases the deformability of the core member and thus of the closure, which in turn results in a worsened sealing capability and thus in increased leakage. In order to avoid this, a thicker and/or denser outer layer or skin is conceivable, as is the incorporation of a stiffer and/or denser central element within the core member. However, either of these approaches increases the total amount of material, thereby diminishing or even eliminating any advantages achieved by reducing the core density. It is also possible to reduce the amount of polymer material by using filler material. Closures are known which incorporate fibers into a polymer matrix. For example, U.S. Pat. No. 5,317,047 describes a stopper made of expandable microspheres, cork powder, and a binder such as a polyurethane or acrylic type glue. The preparation method for closures incorporating cork powder in a polyurethane or acrylic matrix generally involves combining the cork powder with polyurethane or acrylic monomers, oligomers, or prepolymers, and polymerizing in situ. However, residual monomers and low molecular weight compounds such as dimers, trimers, and other oligomers, remain in the matrix and/or in the cork powder. These residual monomers and low molecular weight compounds may not be compatible with food safety considerations, since they can migrate into food products which are in contact with the closure. International Patent Application Publication No. WO 2008/113608 describes closures made of wound cork leafs held together by a bonding agent. Since these closures mainly consist of cork, it is difficult to tailor the properties of the closure to the specific needs of the respective container. U.S. Patent Application Publication No. 2012/0168439 A1 describes a container with a closure for wet environments such as showers employing a wet friction material. The wet friction material can display a hardness from 5 to about 95 Shore A and a coefficient of friction of about 2.0 to 5.3 and does not contain a natural organic filler.
It would be advantageous to be able to control the properties of a closure incorporating filler material, in particular natural organic filler material, in the same way as a closure consisting essentially of one material such as polymer or cork. It would be particularly advantageous to be able to achieve homogeneous properties within such a closure. It would also be advantageous to be able to ensure that the desirable properties for such a closure, for example making it suitable as a closure for a wine bottle, as described herein, are achievable in industrial scale production without significant deviation for individual closures.
According to the present disclosure, natural organic filler preferably means a biodegradable filler material that is obtained from a natural organic material or from a mixture of natural organic materials, which are normally of vegetable origin, with the exception of cork.
In addition to the above, it is often desirable for closures not made of cork to resemble natural cork closures as closely as possible in appearance. Both the longitudinal surface and the flat ends of cylindrical cork closures generally have an irregular appearance, for example showing naturally occurring irregularities in color, structure and profile. Methods have been developed for providing closures from alternative materials such as polymers with a physical appearance similar to natural cork, for example by blending colors to produce a streaking effect in the outer portion of the closure, along the cylindrical axis, or to provide the flat terminating ends of a closure from alternative materials such as polymers with a physical appearance similar to natural cork.
Many industries dealing with natural products and/or natural organic materials, such as the wood industry or the agricultural industry generate large quantities of by-products, for example sawdust or rice straw, that are often considered waste products. It would be advantageous to transform these by-products into a high value composite product. It is known to incorporate natural organic filler materials into composites with polymers. The incorporation of natural organic fillers into a polymer matrix can, however, be detrimental to the processing and performance properties thereof. Composites comprising large amounts of natural organic fillers, for example more than about 50 wt. % thereof, based on the total weight of the composite, tend to have properties such as hardness, density and permeability which make them unsuitable as closures for wine bottles. In addition, crosslinkers and/or compatibilizers are often required in order to improve properties. However, these crosslinkers and/or compatibilizers can raise issues of food safety when used in products which come into contact with foodstuffs. Moreover, natural organic fillers can contain and release substances that affect the sensory perception of food when used in bulk or in composites as packaging material. Examples for such substances are sensory constituents such as phenolic compounds, for example polyphenols, flavonoids, for example proanthocyanidins, and tannins. In addition, natural organic filler materials can have a negative influence on the printability of the resulting composite materials due to low ink absorption. This poses a challenge to employing a natural organic filler component in a closure without deteriorating or spoiling food when the closure is used as a packaging material. In addition, a closure containing the natural organic filler should still provide good mechanical properties, and should not impair printing on the resulting surface. It would be advantageous for a closure to overcome these problems as far as possible.
In addition to the above, it is also desirable, for environmental reasons, that closures made from alternative materials such as polymers are biodegradable. Biodegradable objects are not necessarily made entirely from non-fossil resources. In fact, there are a number of polymers made from fossil resources that can be metabolized, for example by microorganisms, due to their chemical structure. Many polyesters, such as poly(caprolactone) or poly(butylenadipate-co-terephthalate), are made from fossil resources and are biodegradable.
It is, furthermore, often desirable to provide decorative indicia such as letters and ornaments on the surface of wine stoppers (e.g. the crest or emblem of a winery). Natural corks are generally marked by a method commonly referred to as “fire branding,” i.e., by the application of a hot branding tool. Alternatively, natural corks may also be branded by application of colors or dyes. Due to food safety concerns, marking of natural corks with colors or dyes is generally only effected on the curved cylindrical surface of the cork that is not in direct contact with the wine. On the other hand, marking on the flat terminating surfaces of natural corks is generally effected by means of fire branding only since this method does not impose any food safety concerns.
It is also known to brand closures from alternative materials such as polymers. These closures are commonly branded by means of inkjet or offset printing using special dyes or colors approved for indirect food contact. Since such colors and dyes are normally not approved for direct food contact, marking of closures with colors or dyes is generally only effected on the curved cylindrical surface of the closure that is not in direct contact with the wine. Such marking can be on the outermost surface, or on an inner surface which is subsequently covered with an outer, preferably substantially transparent, layer. Marking on the flat terminating surfaces of closures from alternative materials such as polymers is generally only known for injection molded closures, where marking is effected during the molding process of the closure by providing raised portions on the flat terminating surfaces.
Methods are available for marking the flat terminating surface of closures from alternative materials such as polymers that have been manufactured by means of extrusion, in particular by co-extrusion. Laser marking may, in theory, be a feasible method since it allows the avoidance of direct food contact. This method is, however, inherently slow and expensive since it requires the use of special laser dye additives. Also, there have been concerns that laser marking of the flat terminating surfaces of these kinds of closures may adversely change the foam structure of the core element, which may, in consequence, adversely affect the sensitive gas permeation properties of such closures.
A further method involves the application of a decorative layer, in particular of a decorative polymer layer, by means of heat and/or pressure transfer. This method allows for permanent branding of closures from alternative materials without giving rise to concerns relating to food safety and without negatively impacting the gas permeation and/or mechanical properties of closures from alternative materials such as polymers, in particular when they were obtained by co-extrusion.
Therefore, there exists a need for a closure or stopper which particularly comprises at least one of the characteristic features described above, said closure or stopper having a physical appearance and/or tactile characteristics similar in at least one aspect to a natural cork closure, said closure being biodegradable, particularly with only minimal impairment, particularly with no impairment or even with improvement of the other properties of the closure such as, inter alia, OTR, leakage, ease of insertion and removal, compressibility and compression recovery, and/or compatibility with food products.
Other and more specific needs will in part be apparent and will in part appear hereinafter.